I. Field of Invention
This invention applies to the field of artillery projectiles fired from gun platforms and launchers that are known as dual purpose conventional munitions.
II. Background of the Invention
Dual purpose conventional munitions (DPICM) have historically been developed for high spin gun fired artillery projectiles. The changing requirements of the military to achieve longer ranges have dictated the pursuit of fin stabilized guidance projectile warheads with non-spin/low spin characteristics. Projectiles such as the XM 982 and EX-171 extended range DPICM pose unique problems, which require solutions. These are:                a. Grenade fuze arming.        b. Grenade stabilization/orientation.        c. Grenade dispersion for ground pattern effects size and distribution.        d. Need for parasitic dispersal components and hardware, gas generator, and bladder.        e. Maximizing grenade capacity        f. Need for high load bearing joint designs forward and aft of the payload section.        g. Need for a two stage explosion event with use of a pyro delay element design.        
In the past, center core burster charges have been used in low spin rocket systems such as the ER-MLRS. This method dispenses grenades through the thin rocket skin without damage to the grenades. The current method used in both the XM892 and EX-171 projectiles makes use of an expulsion charge, pyrotechnic element, gas generator and expandable metal bladder. Additional hardware such as a spine with pusherplate, payload retaining rods, aft bulk head, retainer, melt plugs and pad, are required.
The above past and current techniques were found to be unsatisfactory for a number of reasons.
First, center core bursters do not work successfully in artillery projectiles since by necessity, projectile body walls are made sufficiently thick to survive high gun setback and spin forces. Grenades passing through projectile body walls, if this were possible to achieve, would result in severely damaged components.
Secondly, the current designs for such precision munitions (non-spin) as the Artillery XM982 and EX-171 actually exacerbate overall problems as stated in paragraph 1 above with the use of inefficient and complex expel and dispense hardware. Moreover, the design approaches do not address the task of projectile spin nor do they address grenade fuze arming and stabilization in the air stream.
Accordingly, it is an object of this invention to eliminate inefficient, complex payload hardware adding to projectile weight and cost.
Another object is to provide a projectile which maximizes projectile grenade capacity and provides, hence, for increased warhead lethality.
Yet, another object is to provide the enabling of grenade fuze arming and stabilization/orientation for grenade impact function, providing for increased reliability.
Another object is to provide for improved ground pattern effects area and grenade distribution in the pattern with improved hit probability and reduced overkill.
Another object is to make use of the more effective M80 Dual Purpose Grenade against soft targets, such as personnel, radar, trucks, and launchers.
Another object is to make use of a wide range of dual purpose submunitions rather than just M80 grenades.
Yet, another object is to improve projectile efficiency in terms of cost effectiveness, i.e. lethality/LB and lethality/$ to defeat.
Another object is to reduce or eliminate the need for difficult load bearing joint designs aft and forward of the payload section with the generation of lower expulsion charge pressures required to expel and dispense the grenade payload.
Yet, another final object is to provide a simple design with the use of only six parts, a pre-engraved rotating band and obturator, a pusher plate, an expulsion charge, projectile payload section and payload canister.
Furthermore this invention, as described applies to both non-spin projectiles such as precision munitions and low spin projectiles such as mortars and rocket systems.
Finally, the last object is to replace the two-stage delay function system of the current XM982/EX-171 designs with a one stage expel and dispense mechanism.